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From:   Greg Kroah-Hartman <gregkh@linuxfoundation.org>
To:     linux-kernel@vger.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        stable@vger.kernel.org, Dan Carpenter <dan.carpenter@oracle.com>
Subject: [PATCH 5.5 157/170] staging: kpc2000: prevent underflow in cpld_reconfigure()
Date:   Tue, 31 Mar 2020 10:59:31 +0200
Message-Id: <20200331085439.631756439@linuxfoundation.org>
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From: Dan Carpenter <dan.carpenter@oracle.com>

commit 72db61d7d17a475d3cc9de1a7c871d518fcd82f0 upstream.

This function should not allow negative values of "wr_val".  If
negatives are allowed then capping the upper bound at 7 is
meaningless.  Let's make it unsigned.

Fixes: 7dc7967fc39a ("staging: kpc2000: add initial set of Daktronics drivers")
Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
Cc: stable <stable@vger.kernel.org>
Link: https://lore.kernel.org/r/20200224103325.hrxdnaeqsthplu42@kili.mountain
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
 drivers/staging/kpc2000/kpc2000/core.c |    4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

--- a/drivers/staging/kpc2000/kpc2000/core.c
+++ b/drivers/staging/kpc2000/kpc2000/core.c
@@ -110,10 +110,10 @@ static ssize_t cpld_reconfigure(struct d
 				const char *buf, size_t count)
 {
 	struct kp2000_device *pcard = dev_get_drvdata(dev);
-	long wr_val;
+	unsigned long wr_val;
 	int rv;
 
-	rv = kstrtol(buf, 0, &wr_val);
+	rv = kstrtoul(buf, 0, &wr_val);
 	if (rv < 0)
 		return rv;
 	if (wr_val > 7)